Optimization of a hybrid gamma camera using LaCl ₃(Ce) scintillators

The optimization of a hybrid collimation camera with both mechanical collimation and electronic collimation was performed by using deterministic and Monte Carlo calculations. Based on the calculations, the design parameters of the hybrid collimation camera were obtained. The optimum thickness of the first detector, which maximized the difference between single and other scattering efficiencies, was 5 ∼ 10 mm for mechanical collimation and 2 ∼ 20 mm for electronic collimation, depending on the incident radiation energy. The number of interaction events in the first detector only or in both the first and the second detectors after scattering in the Pb collimator was small especially at low energies and depended on the thickness of the Pb collimator. The probability of multiple scattering involving both detectors for electronic collimation was negligibly small (<2 %). For high efficiency and small angular resolution, the angle of the second detectors to the system axis was set to 45° and the distance between the first and the second detector was set to 100 mm.